Leaves from multipurpose trees are often rich in N and minerals, and especially important for animal production during critical periods of the year when both the quantity and quality of pasture is limited. However, leaves or foliage of multipurpose tree species often contain high amounts of secondary compounds, especially tannins, which may have a limited impact on increasing the productivity of the animals.
Tannins play a significant role in the nutrition of animals, causing either adverse or beneficial effects on nutrient utilization, health and production. The ideal concentration of CT in forage legumes generally ranges from 20–40 g/kg DM, at which level they may bind with the dietary proteins during mastication and protect the protein from microbial attack in the rumen. CT have biological effects on the control of GIP; possible direct effects could be mediated through CT–nematode interactions, which reduce nematode viability.